Stabilized vinyl chloride composition

ABSTRACT

Vinyl chloride resins are thermally stabilized by incorporating a heterocyclic compound, as represented by Compound A, disclosed herein, which when in the radical, A=S, are thiophene derivatives, when A=--NR, are pyrrolidone derivatives, and when A=O, are tetronic derivatives.

The present invention relates to stabilised vinyl chloride polymercompositions.

Many articles are made by moulding, extruding and casting homo-polymersand co-polymers of vinyl chloride. These processes involve heating thepolymer or co-polymer to temperatures in the order of 180° C. to 200° C.At such temperatures the vinyl chloride polymers and co-polymers undergoconsiderable degradation, resulting in an adverse colour change. Thehigh temperatures further adversely affect the mechanical properties ofthe end product.

To overcome such problems, inorganic salts as well as carboxylic acidsalts of metals have been added to the PVC. The performance of suchmaterials in retarding the degradation of the polymer is enhanced by thefurther addition of co-stabilising additives such as organophosphites,epoxidised esters or oils, hindered phenolic antioxidants and polyols.

U.S. Pat. Nos. 2,307,075 and 2,669,548 describe the beneficial effectsof adding metal chelates of dicarbonyl compounds to the PVC, whereas GB1511621 describes the further improvements offered by a stabilisingcomposition comprising divalent metal salts of carboxylic acids togetherwith an organic dicarbonyl compound.

The present invention seeks to provide an alternative stabilisationsystem.

According to the present invention there is provided a composition basedon homopolymers and/or co-polymers of vinyl chloride comprising thefollowing compounds, expressed by weight relative to the weight ofpolymers/co-polymers:

(a) from 0.1% to 5% of one or more organotin salts and/or one or moredivalent metal salts of a carboxylic acid or phenol; and

(b) from 0.001% to 5% of one or more organic compounds of the generalformula: ##STR1##

in which R₁ represents a linear or branched alkylene or alkenyleneradical having up to 20 carbon atoms, an aralkylene radical having from7 to 20 carbon atoms or an arylene or cycloalkylene radical having from6 to 20 carbon atoms, the cycloalkylene radicals optionally containingcarbon-carbon double bonds; these radicals optionally beingunsubstituted or substituted, by one or more halogen atoms or hydroxylgroups or, for aryl or cycloalkylene radicals, by one or more methyl,ethyl or methoxy radicals, the above mentioned radicals optionally alsobeing modified, by the presence in an aliphatic chain of one or more--O--, --CO-- or --CO₂ -- chain members; R₃ and R₄ are defined as R₁ orH and can be the same or different; A is either O, S or NR₇ with R₇defined as R₁ or H; with the exception that when R₂ =O, A≠O; and R₂represents O, NR₅ or NNHR₅ wherein R₅ is defined as R₁, H or C(S)NHR₆wherein R₆ is defined as R₁ or H; or R₂ represents the following:##STR2##

wherein n is an integer between 1 and 10.

Preferably the composition comprises from 0.001% to 1% of compound A.

Amongst these compounds "A" can be mentioned the following:

N-phenyl-3- 2-isopropylamine)ethylidene!-pyrrolidine-2,4-dione,

N-phenyl-3-acetyl-5-methylpyrrolidine-2,4-dione,

N-p-methoxyphenyl-3-acetylpyrrolidine-2,4-dione,

N-benzyl-3-acetylpyrrolidine-2,4-dione,

N-isopropyl-3-acetylpyrrolidine-2,4-dione,

N-phenyl-3-acetylpyrrolidine-2,4-dione,

3- 2-(4-methylphenylhydrazine)-ethylidene!-tetronic acid

N-methyl-3-acetylpyrrolidine-2,4-dione,

N-phenyl-3- 2-(isopropylamino)ethylidene!-pyrrolidine-2,4-dione

N-p-methylphenyl-3-acetylpyrrolidine-2,4-dione,

3- 2-(4-methylphenyl-hydrazine)-ethylidene!-tetronic acid

N-phenyl-3-benzoylpyrrolidine-2,4-dione,

3-acetyltetrahydrothiophen-2,4-dione, or ##STR3## where n=1,1.5,2,2.5,3,3.5,4,4.5 or 5.

The best all round performance is obtained with the productN-phenyl-3-acetylpyrrolidine-2,4-dione (Compound B). ##STR4##

Thus relating back to the general formula A; R₁ =alkyl, R₂ =O, R₃ =R_(H)=H and A=NR₇ where R₇ =phenyl.

Favourable results have also, however, been obtained with the followingproducts:

(a) A=NR₇, R₁ =methyl, R₂ =O, R₃ =R₄ =H where R₇ =methyl, isopropyl,benzyl, p-tolyl and p-methoxyphenyl i.e. where R₇ =alkyl, aralkyl andsubstituted phenyl respectively;

(b) A=NR₇, R₁ =aryl, R₂ =O, R₃ =R₄ =H, R₇ =phenyl;

(c) A=NR₇, R₁ =methyl, R₂ =O, R₃ =methyl, R₄ =H, R₇ =phenyl;

(d) A=N-phenyl, R₁ =methyl, R₃ =R₄ =H, R₂ =NH-alkyl and when R₂=N-alkyl.

The synthesis of the pyrrolidine compounds named above is described byR. N. Lacey in J.Chem.Soc. 1954, pages 850-854. The synthesis of thetetronic acid derivatives is described in J.Chem.Soc. 1943, pages241-242 by W. Baker, K. D. Grice and A. B. A. Jansen and of the3-acetyltetrahydrothiophen-2,4-dione in J.Chem.Soc 1968, pages1501-1505.

The heat stability of the compounds mentioned above in polyvinylchloride formulations have been established.

The phrase "compositions based on polyvinyl chloride" used herein shouldbe understood to include compositions comprising any homopolymer ofco-polymer of vinyl chloride including chlorinated vinyl chloridepolymers and optionally any adjuvants employed to facilitate processingor to enhance the properties of the end product.

Any suitable organotin salt may be used such as methyl-, butyl-, andoctyltin carboxylate, maleic acid half ester and mercaptoester salts.

The divalent metal salts of carboxylic acids preferably comprise barium,cadmium, zinc, calcium, magnesium or (less desirably) lead salts ofsaturated or unsaturated aliphatic acid or aromatic acids. In the caseof zinc, basic (acid deficient) salts may optionally be employed. Bariumand calcium salts of phenol or substituted phenols and optionally basic(carbonated) phenate and carboxylate salts of these metals can also beemployed. The metal salts are preferably provided in combinations suchas barium-cadmium salts, barium-zinc salts or calcium-zinc salts.Suitable salts include acetates, ethyl hexanoates, octoates, stearates,oleates, laurates, palmitates, myristates, ricinoleats, benzoates(including alkyl substituted benzoates) phthalates, phenates and nonylphenates. Optionally these divalent metal salts can be used incombination with carboxylic acid salts of monovalent metals, for examplesodium, potassium and/or trivalent metals, for example aluminium.Furthermore, inorganic metal salts can be included. Such products can beoxides, carbonates, sulphates, perchlorates, magnesium/aluminium andmagnesium/aluminium/zinc hydroxycarbonates, calcium/aluminiumhydroxycarbonates, calcium/aluminium hydroxyphosphite products.

Optional adjuvants include any of the following: organophosphite esters,for example triaryl phosphites such as triphenyl phosphite,tris(nonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, alkarylphosphites such as monooctyl diphenylphosphite, dioctylphenyl phosphite,mixed alkyl nonylphenyl phosphites, trialkyl phosphites such as tridecylphosphite, trioleyl phosphite, tristearyl phosphite, oligo phosphitessuch as those based on pentaerythritol, dipropylene glycerol andbisphenols.

Antioxidants, for example, phenolic antioxidants such as2,6-di-t-butyl-4-methylphenol, styrenated phenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-bis-(4-hydroxyphenol) propane,octadecyl-3-(3',5'-di-t-butyl-4-hydroxyphenol) propionate,pentaerythritol tetrakis 3',5'-di-t-butyl-4-hydroxyphenol)propionate!.

Ultraviolet absorbers, for example benzophenones such as2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone,benzotriazoles such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole,salicylates such as phenyl salicylate, nickel salts such as nickelbis(octylphenyl sulphide) and nickel bisO-ethyl(3,5-di-t-butyl-4-hydroxybenzyl)!phosphonate, hindered aminessuch as bis(2,2,6,6-tetramethylpiperidinyl-4)sebacate.

Polyol co-stabilisers such as pentaerythritol, dipentaerythritol,tris(hydroxyethyl) isocyanurate, mannitol, sorbitol, trimethylolpropane,glycerol, propylene glycol, ditrimethylolpropane and the esters of theseproducts formed with aliphatic and aromatic monocarboxylic ordicarboxylic acids.

Antistatic agents such as ethylene condensates, carbowax, glycerolmonostearate, alkylsulphonates.

Lubricants such as calcium stearate, zinc stearate, fatty acid estersand amides, distearyl phthalate, stearyl alcohol, stearic acid,polyethylene wax.

Flame retardants such as antimony trioxide, aluminium hydroxide, zincstannate.

The homopolymers and co-polymers can be used in rigid or flexibleformulations. In flexible formulations commonly used plasticisersinclude, for example, phthalic acid esters such as dimethyl phthalate,dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, aliphaticmonobasic acid esters such as butyl oleate, glycerol monoleate, butylstearate, octyl stearate, butyl epoxy stearate, octyl epoxy stearate,epoxidised soya bean oil, epoxidised linseed oil, aliphatic dibasic acidesters such as diisodecyl adipate, dioctyl adipate, dibutyl adipate,higher molecular weight (polymeric plasticisers) based on dibasic acidswould also be included, as would trimellitate esters and phosphoric acidesters such as tributyl phosphate, triphenyl phosphate, tri-2-ethylhexylphosphate.

In rigid formulations it is possible to include impact modifiers suchas, for example, chlorinated polyethylene, butadiene/styrene co-polymersor butadiene/styrene/acrylonitrile terpolymers. Acrylic impact modifiersand process aids can also be included.

Miscellaneous additives such as fillers and pigments could be used inboth the flexible and rigid polymer applications.

The stabilisers according to the invention can be incorporated at thesame time as the other adjuvants. Alternatively, they may be combinedwith certain of the additives to produce a stabiliser composition whichcan then be subsequently incorporated into the chlorinated polymer.Methods of production of such stabilising combinations are well knownwithin the industry.

Various methods are available for the processing of stabilised PVCformulations these include calendering, rotational moulding, spreadcoating, slush moulding, extrusion, injection moulding, blow-moulding.The stabiliser compositions described by the invention can be used inaccordance with each of these techniques.

The following examples provide additional information to furtherillustrate the invention.

EXAMPLES 1-3

A The sample compounds were tested in the formulation given below whichcanbe used for the manufacture of bottles

    ______________________________________                                        Composition A - all amounts are given in phr.                                 ______________________________________                                        Suspension polymerised PVC resin (K-57)                                                               100                                                   Impact modifier, a co-polymer of                                                                      13                                                    methylmethacrylate butadiene and                                              styrene (sold under the trade name)                                           Paraloid BTA736S)                                                             Process aid (Paraloid K175)                                                                           1                                                     Expoxidised Soya Bean Oil                                                                             5                                                     Calcium Stearate        1                                                     Zinc Stearate           0.7                                                   Tris(nonylphenyl) phosphite                                                                           0.3                                                   ______________________________________                                    

121 g of this mixture was taken as example 1. For examples 2 and 3, 121g of Composition A was combined with 0.02 g of stearoylbenzoyl methane(soldunder the trade name Rhodiastab 50) andN-phenyl-3-acetylpyrrolidine-2,4-dione respectively.

The mixtures were mixed by hand before being placed on an oil heatedrolling mill under the conditions described in Table 1. After themilling time, the samples were removed as sheets. Test pieces of size410 mm×20 mm were cut from the prepared sheets and placed in a testovenat 180° C. (Mathis Thermotester Type LTF-ST). The yellowness index(YI of the test sample) was determined according to BS2782:Part 5,Method 530A. The results are shown in Table 2.

                  TABLE 1                                                         ______________________________________                                        Mill Conditions                                                               ______________________________________                                        Roll diameter          110 mm                                                 Front roll temperature 165° C.                                         Back roll temperature  161° C.                                         Front roll speed       26.6 rpm                                               Friction Ratio         1.10                                                   Nip thickness          0.5 mm                                                 Milling time           3 mins                                                 ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                               Y.I. after oven test in minutes                                        Example  2     6        10  14     18   20                                    ______________________________________                                        1        45    76       96  106    106  107                                   2        32    42       45  51     61   70                                    3        21    32       40  50     59   62                                    ______________________________________                                    

B EXAMPLES 4-9

The example compounds were tested in the semi-rigid, pigmented PVCformulation below, which uses a barium-zinc stabiliser system.

    ______________________________________                                        Composition B                                                                 ______________________________________                                        Suspension polymerised PVC resin (K-64)                                                              100                                                    Dioctyl phthalate      27.5                                                   Epoxidised alkyltallate                                                                              3                                                      Stearic Acid           0.26                                                   Titanium dioxide (sold as the trade name                                                             10                                                     R-TC30)                                                                       Diphenyl isooctyl phosphite                                                                          0.67                                                   Diphenyl phosphite     0.05                                                   Basic zinc octoate (22% Zn)                                                                          0.12                                                   Carbonated barium alkylphenolate (28% Ba)                                                            0.38                                                   Butoxyethoxyethanol    0.27                                                   ______________________________________                                    

71.13 g of Composition B was taken as example 4. For examples 5-9 thisamount of Composition B was combined with 0.01 g of dibenzoylmethane,0.01g of N-phenyl-3-benzoylpyrrolidine-2,4-dione, Compound withstructure X, n=3, N-p-methoxyphenyl-3-acetylpyrrolidine-2,4-dione, and3-acetyl-2,4-dioxotetrahydrothiophen respectively. These mixtures weretreated in an identical manner to that described in section A, apartfrom the mill nip thickness which was 0.4 mm. The yellowness indices aregiven in table 3.

                  TABLE 3                                                         ______________________________________                                        Y.I. after oven test in minutes                                               Example 0      2     4    6    8     10   12    14                            ______________________________________                                        4       3.6    4.6   6.5  13.9 18.5  22.6 25    26.5                          5       3.3    4.1   4.7  8    14.9  18   21.3  23.8                          6       3.6    3.8   4    4.5  6     7    9.4   12.2                          7       2.5    3.1   3.1  3.2  3.7   4.3  5.6   7.2                           8       2.6    2.8   3.1  3.2  3.7   4.6  5.2   6.8                           9       2.9    2.9   3.1  4.3  6     10.5 13.3  16.3                          ______________________________________                                    

C EXAMPLES 10-13

The example compounds were tested in the semi-rigid, pigmented PVCformulation using the dynamic mill stability test. The Barium-Zincstabilised system described in Composition B was taken as the baseformulation for this test.

Example 4 is 142.25 g of Composition B, and example 5 is 142.25 g ofComposition B combined with 0.02 g of dibenzoylmethane. Examples 10-13respectively are 142.25 g of Composition B combined with 0.02 ofN-phenyl-3-acetylpyrrolidine-2,4-dione, 0.02 g ofN-isopropyl-3-acetylpyrrolidine-2,4-dione, 0.02 g of N-phenyl-3-2-(isopropylamino)ethylidene!pyrrolidine-2,4-dione and 0.02 g ofN-phenyl-3-acetyl-5-methylpyrrolidine-2,4-dione. These mixtures weremixed by hand before being placed on an oil heated rolling mill underthe conditions described in Table 4. Test pieces of size 20 mm×30 mmwere taken from the mill at 5 minute intervals and the yellowness indexmeasured according to the procedure described under BS2782:Part 5;Method 530A. The results are shown in Table 5.

                  TABLE 4                                                         ______________________________________                                        Mill Conditions                                                               ______________________________________                                        Roll diameter          152 mm                                                 Front roll temperature 183° C.                                         Back roll temperature  180° C.                                         Front roll speed       28.8 rpm                                               Friction Ratio         1.04                                                   Nip thickness          1.3 mm                                                 ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                                Y.I. after mill stability test in minutes                             Example   0     5        10   15     20   25                                  ______________________________________                                        4         5.6   12       17.8 20     22.1 21.3                                5         3.8   7.7      8.7  10.6   14.3 15.7                                10        3.2   3.8      4.6  5.3    6.2  7.9                                 11        3.5   4.0      4.5  5.3    7.3  9.4                                 12        3.4   4.2      4.9  5.9    7.5  9.7                                 13        3.7   4.4      5.1  5.7    7.5  9.6                                 ______________________________________                                    

D EXAMPLES 14-17

The examples below use a flexible clear PVC formulation incorporating acalcium/zinc stabiliser system.

    ______________________________________                                        Composition D                                                                 ______________________________________                                        Suspension polymerised PVC resin (K-71)                                                              100                                                    Dioctyl phthalate      45                                                     Epoxidised alkyltallate                                                                              3                                                      Stearic Acid           0.26                                                   Diphenyl isooctyl phosphite                                                                          1                                                      Basic zinc octoate (22% Zn)                                                                          0.12                                                   Carbonated Calcium Carboxylate (10% Ca)                                                              0.3                                                    Butoxyethoxyethanol    0.61                                                   ______________________________________                                    

75.15 g of Composition D was taken as example 14. For examples 15-17this amount of Composition D was combined with 0.015 g ofdibenzoylmethane; 0.015 g of N-isopropyl-3-acetylpyrrolidine-2,4-dioneand with 0.015 N-benzyl-3-acetylpyrrolidine-2,4-dione respectively.These mixtures treated in an identical manner to that described inSection B. The yellowness indices are given in table 6.

                  TABLE 6                                                         ______________________________________                                               Y.I. after oven stability test in minutes                              Example  0       4     8     12  16    20   24                                ______________________________________                                        14       3.2     3.6   4.4   6.9 8.5   10.0 10.3                              15       4.0     4.3   4.5   5.4 6.3   7.2  7.5                               16       2.9     2.9   3.0   5.0 5.1   7.2  9.0                               17       2.6     2.7   3.4   4.8 5.0   6.5  8.7                               ______________________________________                                    

E EXAMPLES 18-21

The examples below use a flexible clear PVC plastisol formulation with aBarium/Zinc stabiliser system

    ______________________________________                                        Composition E                                                                 ______________________________________                                        Emulsion PVC resin (K-72)                                                                             100                                                   Dioctylphthalate        50                                                    Carbonated Barium Alkylphenolate (28% Ba)                                                             0.5                                                   Basic zinc octoate (22% Zn)                                                                           0.16                                                  Diphenyl isooctyl phosphite                                                                           0.9                                                   Diphenyl phosphite      0.2                                                   Butoxyethoxyethanol     0.21                                                  ______________________________________                                    

151.97 g of Composition E were taken as example 18. For examples 19-21thisamount of Composition E was combined with 0.03 g ofdibenzoylmethane; 0.03 g of N-benzyl-3-acetylpyrrolidine-2,4-dione; 0.03g of 3- 2-(4-methylphenyl-hydrazine)-ethylidene!-tetronic acid.

The compositions described above were mixed initially by hand and thenusing the laboratory triple roll mill for a period of 10 minutes. Theblends were then deaerated using a Collin (type 110) laboratory mixerbefore being spread on to a release paper to a thickness of 0.5 mm. Theplastisols were then gelled at 185° C. for 1 minute. Test pieces ofsize410 mm×20 mm were cut from the gelled sheet and placed in a testoven at180° C. (Mathis Themotester Type LTF-ST). The yellowness index of thetest sample was determined according to BS2782:Part 5; Method530A. Theresults are shown in table 7.

                  TABLE 7                                                         ______________________________________                                        Y.I. after oven stability test in minutes                                     Example                                                                              0       1      2    3    4    5    6     7                             ______________________________________                                        18     28.4    36     46   52   67.4 87.4 102   115                           19     16      18.6   22.3 30   37.3 66   80.4  96.4                          20     13.6    14.2   15   16   17.7 28.2 35    50                            21     15.3    17.2   22   28   38.3 53.4 70.9  81                            ______________________________________                                    

F. EXAMPLES 22-25

The examples below use a white pigmented PVC plastisol formulation,stabilised by a Barium/Zinc composition.

    ______________________________________                                        Composition F                                                                 ______________________________________                                        Emulsion PVC resin (K-72)                                                                              100                                                  Dioctylphthalate         50                                                   Titanium dioxide sold under                                                                            10                                                   the trade name Tioxide RFC-5                                                  Carbonated Barium Alkylphenolate (28% Ba)                                                              0.5                                                  Basic zinc octoate (22% Zn)                                                                            0.16                                                 Diphenyl isooctylphosphite                                                                             0.9                                                  Diphenylphosphite        0.2                                                  Butoxyethoxyethanol      0.21                                                 ______________________________________                                    

161.97 g of Composition F were taken as example 22. For examples 23-25thisamount of Composition F was combined with 0.03 g ofdibenzoylmethane, 0.03 g ofN-phenyl-3acetyl-5-methylpyrrolidine-2,4-dione; 0.03 g ofN-phenyl-3-acetylpyrrolidine-2,-4-dione. These mixtures were treated inexactly the same manner as that described in section E. The yellownessindices are given in table 8.

                  TABLE 8                                                         ______________________________________                                                Y.I. after oven stability test in minutes                             Example   0      2        4    6      8    10                                 ______________________________________                                        22        17.8   29.4     41.8 58.6   70   76.5                               23        10.6   12.6     21.9 52.6   70   78.8                               24        10.    10.5     12.2 20     31   51.5                               25        8.2    14.5     17.7 34.4   51.3 63.4                               ______________________________________                                    

G EXAMPLES 25-27

The examples below use a rigid PVC formulation stabilised by abutylthiotinstabiliser.

    ______________________________________                                        Composition G                                                                 ______________________________________                                        Suspension polymerised PVC resin (K-57)                                                                 100                                                 Impact modifier, a copolymer of                                                                         5                                                   methylmethacrylate, butadiene and styrene                                     (sold under the trade name Paraloid BTA736S)                                  Process aid (Paraloid K175)                                                                             1.70                                                Montanic Acid Ester       0.3                                                 Hydrogenated Castor Oil   0.5                                                 Dibutyltin bis(ethylhexylthioglycollate)                                                                1.5                                                 containing 5% butylin tris(ethylhexylthioglycollate)                          ______________________________________                                    

109 g of this mixture was taken as example 25. For example 26, 109 g ofComposition G was combined with 0.03 g of dibenzoylmethane and forexample27, 109 g of Composition G was combined with 0.03 g ofN-phenyl-3-acetylpyrrolidine-2,4-dione.

The mixtures were mixed by hand and treated as described in section Aexcept that the test oven was maintained at 185° C. The yellownessindices are given in table 9.

                  TABLE 9                                                         ______________________________________                                                Y.I. after oven stability test in minutes                             Example   0     6        12  18     24   30                                   ______________________________________                                        25        2.5   3.2      3.9 6.6    11.4 16.6                                 26        2.8   3.0      3.9 7.9    11.9 16                                   27        2.4   3.3      3.8 6.3    9    12.6                                 ______________________________________                                    

H. EXAMPLES 28-30

The example compounds were tested in a flexible clear PVC formulationstabilised by a Calcium/Zinc/Hydrotalcite solid system.

    ______________________________________                                        Composition H                                                                 ______________________________________                                        Suspension PVC resin (K-71)                                                                          100                                                    Dioctyl phthalate      50                                                     Calcium Stearate       0.5                                                    Zinc Stearate          0.5                                                    Mg/Al/Zn Hydroxycarbonate (sold under                                                                0.3                                                    the trade name of Alcamizer 4)                                                Bisphenol A            0.1                                                    Tris(nonylphenyl) phosphite                                                                          1.0                                                    ______________________________________                                    

152.4 g of Composition H were taken as example 28. For example 29, 152.4g of Composition H were combined with 0.025 g of benzoylstearoylmethane. For example 30, 152.4 g of Composition H were combined with0.025 g of N-phenyl-3-acetyl-pyrrolidine-2,4-dione. These mixtures weretreated in anidentical manner to that described in section A. Theyellowness indices aregiven in table 10.

                  TABLE 10                                                        ______________________________________                                               Y.I. after oven stability test in minutes                              Example  0         5     10      15   20                                      ______________________________________                                        28       0.6       1.4   9.5     10.0 15.5                                    29       1.4       2.3   4.2     5.7  8.0                                     30       0.1       1.5   1.5     3.6  6.8                                     ______________________________________                                    

I EXAMPLES 31-35

The example compounds were tested in a filled plastisol PVC formulationstabilised by a liquid barium/zinc system.

    ______________________________________                                        Composition I                                                                 ______________________________________                                        Emulsion PVC resin (K-79)                                                                            100                                                    Calcium carbonate      50                                                     Dioctylphthalate       60                                                     Carbonated Barium alkylphenolate (28% Ba)                                                            0.5                                                    Basic zinc octoate (22% Zn)                                                                          0.16                                                   Diphenyl isooctylphophite                                                                            0.9                                                    Diphenyl phosphite     0.2                                                    Butoxyethoxyethanol    0.2                                                    ______________________________________                                    

Composition I was mixed in a paddle mixer for 7 minutes. 105.98 g ofComposition I was taken as example 31. For examples 32-35 this amount ofComposition I was combined with 0.0125 g of dibenzoylmethane, 0.0125 gof N-benzyl-3-acetylpyrrolidine-2,4-dione, 0.005 g ofN-benzyl-3-acetylpyrrolidine-2,4-dione, 0.005 g of N-phenyl-32-isopropylamino)ethylidine!pyrrolidine-2,4-dione. These mixtures wereplaced on an oil heated rolling mill under the conditions described inTable 11

                  TABLE 11                                                        ______________________________________                                        Roll diameter          110 mm                                                 Front roll temperature 160° C.                                         Back roll temperature  160° C.                                         Front roll speed       26.6 rpm                                               Friction ratio         1.10                                                   Nip thickness          0.4 mm                                                 Milling time           2 minutes                                              ______________________________________                                    

Test pieces were cut from the prepared sheets and placed in a test ovenat 190° C. (Mathis Thermotester LTF-ST). The yellowness indices aregiven in Table 12.

                  TABLE 12                                                        ______________________________________                                        Y.I. after time in oven in mins                                               Example 0      2       4    6     8    10    12                               ______________________________________                                        31      14.5   19      30.9 44.3  57.3 70    88.2                             32      11.1   11.8    13   16.7  26.4 40.8  59.4                             33      9.5    10.9    11.9 13.4  16.6 20.5  31.4                             34      10.7   12.2    15.8 19.1  27.9 35.7  50.6                             35      12.8   16.6    24   29.4  39.4 46.2  56.3                             ______________________________________                                    

We claim:
 1. A composition based on homopolymers and/or copolymers ofvinyl chloride comprising the following compounds, expressed by weightrelative to the weight of the polymers:(a) from 0.1% to 5% of one ormore organotin salts and/or one or more divalent metal salts of acarboxylic acid or phenol; and (b) from 0.001% to 5% of one or moreorganic compounds of the general formula ##STR5## in which R₁ representsa linear or branched alkylene or alkenylene radical having up to 20carbon atoms, an aralkylene radical having from 7 to 20 carbon atoms oran arylene or cycloalkylene radical having from 6 to 20 carbon atoms,the cycloalkylene radicals optionally containing carbon-carbon doublebonds; these radicals optionally being unsubstituted or substituted, byone or more halogen atoms or hydroxyl groups or, for aryl orcycloalkylene radicals, by one or more methyl, ethyl, or methoxyradicals, the above mentioned radicals optionally also being modified bythe presence in an aliphatic chain of one or more --O--, --CO-- or--CO₂₋ chain members; R₃ and R₄ are defined as R₁ or H and can be thesame or different; A is either O, S or NR₇, with R₇ defined as R₁ or H;with the exception that when R₂ =O, A≠O; and R₂ represents O, NR₅ orNNHR₅ wherein R₅ is defined as R₁, H or C(S)NHR₆ wherein R₆ is definedas R₁ or H; or R₂ represents the following: ##STR6## wherein n is aninteger between 1 and
 10. 2. A composition as claimed in claim 1,wherein the composition comprises from 0.001% to 1% by weight of anorganic compound of the general formula of Compound A relative to theweight of polymers.
 3. A composition as claimed in claim 1 wherein theorganic compound of the general formula Compound A comprises any of thefollowing:N-phenyl-3-2-isopropylamine)ethylidene!-pyrrolidine-2,4-dione,N-phenyl-3-acetyl-5-methylpyrrolidine-2,4-dione,N-p-methoxyphenyl-3-acetylpyrrolidine-2,4-dione,N-benzyl-3-acetylpyrrolidine-2,4-dione,N-isopropyl-3-acetylpyrrolidine-2,4-dione,N-phenyl-3-acetylpyrrolidine-2,4-dione, 3-2-(4-methylphenylhydrazine)-ethylidene!-tetronic acidN-methyl-3-acetylpyrrolidine-2,4-dione, N-phenyl-3 -2-(isopropylamino)ethylidene!-pyrrolidine-2,4-dione,N-p-methylphenyl-3-acetylpyrrolidine-2,4-dione, 3-2-(4-methylphenyl-hydrazine)-ethylidene!-tetronic acid, N-phenyl-3-benzoylpyrrolidine-2,4-dione, 3-acetyltetrahydrothiophen-2,4-dione, or##STR7## where n=1, 1.5,2,2.5,3,3.5,4,4.5 or
 5. 4. A composition asclaimed in claim 1, wherein the organic compound of the general formulaof Compound A comprises the following substituents: R₁ =alkyl, R₂ =O, R₃=R4=H and A=NR₇ where R₇ =phenyl.
 5. A composition as claimed in claim1, wherein the organic compound of the general formula of Compound Acomprises the following substituents: A=NR₇, R₁ =methyl, R₂ =O, R₃ =R₄=H where R₇ =alkyl, aralkyl or substituted phenyl.
 6. A composition asclaimed in claim 1, wherein the organic compound of the general formulaof Compound A comprises the following substituents: A=NR₇, R₁ =aryl, R₂=O, R₃ =R4=H, R₇ =phenyl.
 7. A composition as claimed in claim 1,wherein the organic compound of the general formula of Compound Acomprises the following substituents: A=NR₇, R₁ =methyl, R₂ =O, R₃=methyl, R₄ =H, R₇ =phenyl.
 8. A composition as claimed in claim 1,wherein the organic compound of the general formula of Compound Acomprises the following substituents: A=N-phenyl, R₁ =methyl, R₃ =R₄ =H,R₂ =NH-alkyl and when R₂ =N-alkyl.
 9. A composition as claimed in claim1 wherein the organotin salt comprises any of the following: methyl-,butyl-, or octyltin carboxylate, maleic acid half ester or mercaptoestersalts.
 10. A composition as claimed in claim 1 wherein the metalcomponent of the divalent metal salt comprises any of the following:barium, cadmium, zinc, calcium, magnesium or lead salts, barium-cadmiumsalts, barium-zinc salts or calcium-zinc salts.
 11. A composition asclaimed in claim 1, wherein the composition further comprises carboxylicacid salts of at least one monovalent metal and/or trivalent metal. 12.A composition as claimed in claim 1, wherein the divalent metal saltcomprises any of the following: acetate, ethyl hexanoate, octoate,stearate, oleate, laurate, palmitate, myristate, ricinoleate, benzoate(including alkbenzoate substituted benzoate) phthalate, phenate or nonylphenate.
 13. A composition as claimed in claim 1, wherein thecomposition further comprises at least one inorganic metal derivativesfrom the following: oxides, carbonates, sulphates, perchlorates,magnesium/aluminium and magnesium/aluminium/zinc hydroxycarbonates,calcium/aluminium hydroxycarbonates, calcium/aluminium hydroxyphosphiteproducts.